For example, with an analytical device that uses a sampling method such as a headspace method, a sample, which is an analysis target, is introduced into an analytical section by an autosampler from a sample container in which the sample is sealed. According to this type of analytical device, a liquid or solid sample in the sample container is vaporized due to heat of the sample container being retained, and an upper space (headspace) inside the sample container is filled with sample gas. By inserting a needle into the sample container in this state, the sample gas may be introduced into the analytical section via the needle.
In the case of continuously performing analysis of a plurality of samples, heat of each of a plurality of sample containers is retained, and sample gas is sequentially drawn out from each sample container (for example, see Patent Document 1). Samples may possibly contain a component which is decomposed when heat retention is continued, and thus the heat retention time is desirably fixed for each sample container. Normally, 30 minutes to several hours are required for heat retention, and the time may be longer than the analysis time of each sample. Accordingly, with the configuration described in Patent Document 1, heat retention is performed in an overlapped manner for a plurality of sample containers so as to improve the processing performance.
FIG. 5 is a diagram for describing a mode of autosampling by a conventional headspace method. In this example, a case is described in which a plurality of samples A, B, C, . . . are sequentially introduced into a column of a gas chromatograph and programmed temperature analysis is continuously performed for the samples A, B, C, . . . .
The sample A is introduced into the column from a start timing T111 of the programmed temperature analysis, and analysis is performed until an end timing T112 of the programmed temperature analysis while increasing the temperature of the column. The programmed temperature analysis is thus performed only for a preset analysis time A111, and then the column is cooled. A cooling time A112 of the column changes depending on the room temperature, and the programmed temperature analysis of the next sample B is started after a margin time A113 has passed since a cooling end timing T113. From the start timing T111 of the programmed temperature analysis of the sample A to a start timing T121 of the programmed temperature analysis of the next sample B is a cycle time A101 of the sample A.
The sample B is introduced into the column from the start timing T121 of the programmed temperature analysis, and analysis is performed until an end timing T122 of the programmed temperature analysis while increasing the temperature of the column. The programmed temperature analysis is thus performed only for a preset analysis time B111, and then the column is cooled. In this example, due to a change in the room temperature, a cooling time B112 of the column after the programmed temperature analysis of the sample B is longer than the cooling time A112 of the column after the programmed temperature analysis of the sample A. A margin time B113 from a cooling end timing T123 until start of the programmed temperature analysis of the next sample C is reduced by the amount of increase in the cooling time B112, and a cycle time B101 of the sample B is thereby made the same as the cycle time A101 of the sample A.
The sample C is introduced into the column from the start timing T131 of the programmed temperature analysis, and analysis is performed until an end timing T132 of the programmed temperature analysis while increasing the temperature of the column. The programmed temperature analysis is thus performed only for a preset analysis time C111, and then the column is cooled. A cooling time C112 of the column after the programmed temperature analysis of the sample C is increased as in the case of the cooling time B112 of the column after the programmed temperature analysis of the sample B, and a margin time C113 is reduced to that extent. As a result, a cycle time C101 of the sample C is made the same as the cycle times A101, B101 of the samples A, B.
As described above, according to autosampling by a conventional headspace method, the cycle times A101, B101, C101, . . . of the samples A, B, C, . . . are the same. Specifically, the cycle times A101, B101, C101, . . . of the samples A, B, C, . . . are set to a relatively long time that allows a sufficient margin so that the cycle times A101, B101, C101, . . . become the same even if the cooling times A112, B112, C112, . . . are changed due to a change in the room temperature.
Heat retention times A102, B102, C102, . . . of the samples A, B, C, . . . are fixed. Since the cycle times A101, B101, C101, . . . of the samples A, B, C, . . . are the same, the start timings T111, T121, T131, . . . of the programmed analysis of the samples A, B, C, . . . are at a fixed cycle. Accordingly, heat retention start timings of the samples A, B, C, . . . are also set while being shifted by fixed time intervals D101, D102, . . . .